1. Field of the Invention
The present invention relates to enhanced control of a wafer processing facility. More specifically, the present invention relates to a system, method and medium for the accurate and highly responsive implementation of one or more instructions/functions relating to the production of wafers in a wafer processing facility, and particularly for controlling one or more wafer processing chambers within a wafer processing facility. The present invention accomplishes this by utilizing two or more processors, which may reside in separate computer processor systems, wherein each processor and/or computer processor system is assigned to control, and sample information relating to, one or more designated functions (e.g., temperature, pressure, etc.).
2. Related Art
With each passing year, engineers continue to attempt to squeeze more and more circuits into a smaller and smaller space on integrated circuit chips. As a result, the various films deposited or grown atop the xe2x80x9cwaferxe2x80x9d (or substrate), from which these circuits are designed, also need to become thinner and thinner, allowing smaller and smaller elements (e.g., gates) to be squeezed into a given space. In particular, current designs are moving into the 0.15 to 0.1 micron range (i.e., the minimum horizontal width for an element). At the same time, the industry standard diameters of the semiconductor wafers are expanding from 200 mm to 300 mm. (These wafers are then typically cut into smaller pieces for use in the actual chips).
In general, it has been conventionally important to accurately and expediently control the parameters used in the manufacture of wafers. For example, with regard to temperature, it is desirable to obtain temperature uniformity in the wafer during temperature cycling. Temperature uniformity provides for uniformity of aspects of the end-product wafer, such as layer thickness, resistivity, and etch depth. In addition, temperature uniformity in a wafer is necessary to prevent thermal stress-induced wafer damage such as warpage, defect generation and slip. Such control of temperature also becomes increasingly important as one attempts to increase the rate of wafer production (e.g., wafers per hour), since that requires the duration that the wafer is heated and cooled to be reduced (and, thus, the rates of temperature changes become more extreme). Also, it is often the case that the rapid temperature changes yield better results in the quality of the end-product wafer, as well. Other functions that may also require such control include pressure and the positioning of the wafer within the wafer processing chamber.
Prior wafer processing facilities such as the RTP XEplus Centura and the HTF Centura (with, e.g., LPCVD Polysilicon chambers) from Applied Materials of Santa Clara, Calif. do provide some control of the various functions mentioned above in the course of controlling their wafer processing chambers. However, as critical dimmensions continue to shrink, it becomes increasingly important to more and more accurately and expediently control the functions used in their manufacture. With regard to temperature, for example, the smaller elements will not be created properly, and the wafer itself will be more prone to warpage, if the temperature is not uniformly and expediently controlled.
In practice, it has been found that the control mechanisms of the prior wafer processing facilities mentioned above are unable to adequately fulfill the demands necessary to effectively manufacture the thinner films having greater diameters at the throughput required. For example, it has been found that the amount of information coming in from numerous sensors which must be analyzed and responded to quickly causes significant congestion on the various conduits (e.g., busses) of the computer processing system of the wafer processing facility, and that the constant interruptions that are placed upon the processor (due to, e.g., receipt of sensor information) tend to degrade from the performance of the computer processing system in its attempt to control the parameters of the wafer processing chamber.
Consequently, what is needed is a scheme for responding to the increasing demands arising from the manufacture of the wafers described above such that the necessary functions can be observed and adjusted quickly and in accordance with a set of instructions (i.e., a xe2x80x9crecipexe2x80x9d) dictating the requirements for the manufacture of such wafers.
The present invention solves the problems mentioned above by providing a system, method and medium for controlling a wafer processing chamber using two or more processors (within one or more computer processing systems), wherein specified functions are assigned to each processor. More specifically, some embodiments of the present invention contemplate that each processor has its own communications conduit (e.g., central bus), and that each may reside within its own computer processor system (each computer processor system being in communication with the other), wherein each computer processor system implements specified functions to control and maintain certain parameters involved in the manufacture of the wafer. This allows the present invention to react quickly to maintain rapidly-changing desired conditions within a wafer processing chamber and to maintain a greater degree of uniformity of those conditions throughout the wafer.
Embodiments of the present invention contemplate that the wafer (referring hereafter to the end product wafer plus film) is manufactured in accordance with a recipe (which contains instructions and/or individual functions to be implemented within the wafer processing chamber). Consequently, a focus of at least some aspects of the present invention relates to ensuring that the instructions/functions in the recipe that are followed accurately and expediently.
As indicated above, embodiments of the present invention contemplate that each processor within the one or more computer processor systems is assigned to oversee a particular function (e.g., temperature or pressure). Various embodiments of the present invention further contemplate situations where each instruction step contains multiple functions such as temperature and pressure (or some other situation where multiple functions can run concurrently), and that one of those functions is designated as xe2x80x9ccontrolling.xe2x80x9d For example, a given instruction step might indicate that both the temperature and pressure in a wafer processing chamber need to be increased, and also indicate that xe2x80x9ctemperaturexe2x80x9d is to be xe2x80x9ccontrolling.xe2x80x9d Then, the processor which is assigned to oversee temperature will be in control such that when the temperature reaches the goal indicated by the instruction step, the controlling processor will indicate to the other processors that the next instruction should be implemented, and will itself implement that next step. In this way, critical functions can be selected and implemented quickly and efficiently.